Tracked military vehicles (tanks) sometimes have multiple fuel tanks for such purposes as quicker filling from multiple nozzles, and redundant fail-safe action during enemy attack. In such multiple fuel tank systems the fuel pump(s) draw fuel out of the tanks through suction tubes connected to the tank bottom walls. Should a tank start to run dry it is necessary to close that tank to the suction force; otherwise air flowing from the empty tank into the suction line may prevent the fuel pump from drawing fuel out of the other tanks.
The present invention contemplates the use of a float-operated valve in each tank to close that tank to the suction tube as the liquid level in the tank gravitates down to a predetermined low value, e.g. one inch above the tank bottom wall. A feature of the valve is a pressure-equalization structure that precludes the tube suction from adversely affecting the valve operation. This pressure-equalization feature reduces the size of the float necessary to close or open a given size suction tube.